Photo-chemical production of oximes

ABSTRACT

A HIGH-PRESSURE MERCURY VAPOUR DISCHARGE LAMP FOR CARRYING OUT PHOTO-CHEMICAL REACTIONS COMPRISES AN ENVELOPE DEFINING AN ENCLOSED SPACE, THE ENCLOSED SPACE HAVING THEREIN A DOPING MEDIUM COMPRISING AT LEAST ONE HALIDE OF A METAL OF GROUP 3A (SUCH AS YTTRIUM), WITH WHICH THERE MAY BE ASSOCIATED A HALIDE OF A METAL OF GROUP 3B (SUCH AS THALLIUM) AND/OR A HALIDE OF A METAL OF THE LANTHANIDE GROUP (SUCH AS HOLMIUM), THE CONCENTRATION OF THE DOPING MEDIUM BEING FROM 0.002 TO 1 MG./CC. AND PREFERABLY FROM 0.02 TO 0.5 MG/CC.

Int. Cl. B01j l/JO US. Cl. 204-462 XN 8 Claims ABSTRACT OF THEDISCLOSURE A high-pressure mercury vapour discharge lamp for carryingout photo-chemical reactions comprises an envelope defining an enclosedspace, the enclosed space having therein a doping medium comprising atleast one halide of a metal of Group 3a (such as yttrium), with whichthere may be associated a halide of a metal of Group 3b (such asthallium) and/ or a halide of a metal of the lanthanide group (such asholmium), the concentration of the doping medium being from 0.002 to 1'mg./cc. and preferably from 0.02 to 0.5 mg./cc.

BACKGROUND OF THE INVENTION The lamps generally employed forphotochemical reactions are mercury vapour discharge lamps.

For many of these reactions, it necessary to eliminate a part of theradiation which is harmful to the main reaction and which is responsiblefor secondary reactions. These secondary reactions produce deposits onthe Walls of the lamp, decrease the yield of the reaction andcontaminate the desired product.

In order to obviate these disadvantages, it has been proposed to employvarious filters, in some cases constituted by the very nature of theenvelope of the lamp, or to use various products which may be interposedin the path of the radiation through the reaction medium.

GENERAL DESCRIPTION OF THE INVENTION The applicants have designed andproduced novel lamps exhibiting a predetermined emission spectrum forvarious photochemical reactions by means of which it is possible toobtain a pure product in an optimum yield.

'It is known that the spectral distribution of the emitted radiationdepends essentially upon the nature, upon the quantity and upon therelative proportions of the various elements present in the dischargechamber.

On the other hand, the maximum quantum yield of a particularphotochemical reaction may be established'as a function of the mainlines of the emission spectrum of a lamp, and the variation of thisyield may be established as a function of the concentration and thenature of the reaction medium.

The lamps according to the invention have the advantage of providing aradiation appropriate for the main reactions in an emission range from3600 to 6000 A. while substantially reducing the radiation whichgenerates secondary reactions. Thus, in one mode of application of theselamps such as the photochemical preparation of the cycloalkanone oximesand in particular of cyclododecanone oxime, greatly improved yields ofthe order of 3 to 4 moles/kWh. of pure oxime are obtained.

The work carried out by the applicants has involved them in studying, ina first stage, the influence of various addition agents such as halidesof Groups 3a and 3b of the Periodic System of the Elements, takenseparately or in admixture, and regarded as doping agents, and in336M218 Patented Aug. 1, 1972 ably from 0.02 to 0.5 mg./ cc.

In accordance with one embodiment of the invention, the lamps alwayscomprise a halide of the Group 3a such as an yttrium halide. They maycomprise a mixture of halides of the Groups 3a and 3b such as mixturesof yttrium and indium halides or mixtures of yttrium and thalliumhalides. Finally, there may be associated with all the previouslydescribed doping agents a halide of the lanthanide group such as aholmium halide.

If the mixture of doping agents consists of two halides of metals of theGroups 3a and 311-, for example of yttrium and indium, and of alanthanide halide, for example holmium, the weight ratio of thesehalides may be of the order of:

yttrium halide/ indium halide=1/ 2 holmium halide/ yttrium halide: 1/2

Satisfactory results are obtained when the concentration of the holmiumhalide employed is at most equal to that of the halide of the metal ofthe Groups 3a and 3b employed in a smaller quantity, and notably when itis between 0.01 and 0.15 mg./cc.

In accordance with one form of construction of these lamps, referred toby way of non-limiting example, there is introduced into the enclosedspace of the lamp a mixture of:

Mg./cc. Indium iodide 0.200-0150 Yttrium iodide 0.1000.125 Holmiumiodide 0.050.07

If the emission spectra of these lamps are examined,

and for example that of the lamp doped with yttrium and indium iodides,it is found that the relative power of the radiation below 4000 A. is1.2%, while it is 18% in an undoped mercury vapour lamp.

. Spectral distribution of a lamp containing yttrium and indium iodides:

Relative Power for radiation each wavepower, length in 7\ A. percentwatts DESCRIPTION OF THE PREFERRED EMBODIMENTS In accordance with oneembodiment of the invention, the halogen or halogens may be introducedinto the lamp in a form in which they are not combined with the elementsbelonging to the above-designated groups, which are preferably yttrium,indium, thallium and holmium. The introduced halogen must be presenttherein in a proportion at least equivalent to the number ofgrammemolecules of the elements of the Groups 3a and 3b and of thelanthanides contained in the lamp.

The following examples, which are given by Way of indication but have nolimiting character, will enable the appreciable increases in yieldobtained with the lamps according to the invention to be appreciated.

By way of comparison, there are first described examples carried outwith lamps containing no iodide of the lanthanide group.

EXAMPLE 1 Into a reactor consisting of a cylindrical Pyrex glassreceptacle having an internal diameter of 110 mm. and a height of 200mm., as described in French Pat. 1,331,478 and provided with an undopedmercury vapour lamp of 25 w. enclosed in a Pyrex glass tube, throughwhich a current of cooling water is passed, are introduced 150 g. ofcyclododecane in solution in 150 g. of carbon tetrachloride, and then 50g. of 99% sulphuric acid. The mixture is stirred and the temperature ismaintained between 15 and 20 C. There are introduced 4.3 g. of nitrosylchloride in solution in carbon tetrachloride and the mercury vapour lampis ignited.

First after irradiation for 2 hours and again after irradiation for 4hours, there are introduced 4.3 g. of 10% nitrosyl chloride in carbontetrachloride (i.e. in all 12.9 g. of nitrosyl chloride).

When the decolouration of the organic solution is complete, which is soafter irradiation for 7 hours, the apparatus is stopped, the sulphuricacid layer is separated and the organic solution is then washed with alittle 70% sulphuric acid.

The sulphuric acid solutions are combined and poured on to crushed ice.The oxime precipitates, and is filtered, washed with water and, afterdrying, crystallised from cyclohexane. There are thus obtained 32.9 g.of cyclododecanone oxime, M.P. 132133 C., i.e. a yield of 188 g./kwl1.

EXAMPLE 2 The procedure of Example 1 is followed with a 25-watt lampdoped with yttrium iodide. It is found that it is necessary to introduce20.1 g. of nitrosyl chloride in 3 lots in order to decolourise thesolution. After irradiation for 7 hours, there are obtained 53.9 g. ofoxime, which is a yield of 310.20 g. of oxime/kwh.

EXAMPLE 3 The procedure of Example 1 is followed with a lamp doped witha mixture of yttrium and indium iodides.

22 g. of nitrosyl chloride are introduced in 3 lots in order todecolourise the solution, and after irradiation for 7 hours there areobtained 59.5 g. of cyclododecanone oxime, which is a yield of 340g./kwh.

4 EXAMPLE 4 The procedure of Example 1 is followed with a lamp dopedwith a mixture of yttrium and thallium iodides.

20.1 g. of nitrosyl chloride are introduced in 3 lots, and afterirradiation for 7 hours there are obtained 54.79 g. of cyclododecanoneoxime, which is a yield of 319 g. of

oxime per kwh.

EXAMPLE 5 Example 2 is repeated with a lamp comprising a mixture ofyttrium and holmium iodides after the addition of 25 grammes of NOCl.There are obtained 66.1 g. of cyclododecanone oxime, which is a yield of377 g./kwh.

EXAMPLE 6 The procedure of Example 3 is followed, using a lampcomprising holmium iodide in addition to yttrium and indium iodides.

It is necessary to introduce 46.3 g. of nitrosyl chloride, and 126 g. ofoxime are obtained, which is an oxime yield of 720 g./kwh.

EXAMPLE 7 EXAMPLE 8 Into a reactor consisting of a cylindrical Pyrexglass receptacle having a diameter of 130 mm. and a height of 350 mm.and provided with a stirrer, a thermometer, and tubes for theintroduction and discharge of gas are introduced 600 g. of cyclododecanein solution in 3000 g. of carbon tetrachloride and g. of sulphuric acid.The lamp employed is a 75-watt high-pressure mercury vapour lampvertically mounted on the axis of the reactor and in a Pyrex glassjacket cooled by a current of Water. The stirrer is started and the lampis ignited.

A gaseous mixture of nitrosyl chloride and hydrogen chloride is thenintroduced at a rate of 30 litres per hour at the bottom of the liquid,the mole ratio of NOCl/HCI being 1/8. The temperature of the reactionmixture is maintained between 15 and 20 C. After a reaction period of 6hours, the irradiation is stopped and the sulphuric acid layer isdecanted and poured on the crushed ice, and after neutralisation withdilute caustic soda there are obtained 90 g. of cyclodoecanone oxime,i.e. a yield of 200 g. of oxime per kwh.

EXAMPLE 9 The operation is carried out in the same reactor as in Example8 with a 75-watt lamp doped with indium and yttrium iodides. 400 g. of99% sulphuric acid are added and the gaseous nitrosyl chloride/hydrogenchloride mixture is introduced at a rate of 75 litres per hour. Afterirradiation for 6 hours, 265.5 g. of cyclododecanone oxime arecollected, which is a yield of 592.9 g./kwh.

EXAMPLE 10 The procedure of Example 8 is followed with a 75-watt lampdoped with yttrium, indium and holmium iodides. 450 g. of 99% sulphuricacid are introduced and the rate of flow of the nitrosylchloride/hydrogen chloride mixture is 90 litres per hour. Afterirradiation for 6 hours, there are obtained 324 g. of cyclododecanoneoxime, which is a yield of 720 g./kwh.

EXAMPLE 1 1 Into a reactor identical to that described in Example 9 andprovided with the same lamp are introduced 3 litres of cyclohexane. 450g. of sulphuric acid are added and the gaseous nitrosylchloride/hydrogen chloride mixture is run in at a speed of 90 litres perhour. After irradiation for 6 hours, there are obtained 216 g. ofcyclohexanone oxime, which is a yield of 480 g. kWh.

The following Table I shows the comparisons of yields obtained withlamps according to the invention and undoped lamps, taking as referencethe yield obtained in Example 8 (200 g. of oxime per kwh.).

TABLE I Ratio of the yields Cyclododec- Consumpof doped anone tion,lamps to oxime, kwhJkg. undoped Lamps gJkwh. oxime lamp Example 1, Hg188 5. 3 Example 8, Hg 200 1 Iodides of- Example 2, Y 310 3.2 1.55Example 5, Y+H0 377 2.6 1.88

Iodides of- Example 3, Y+In 340 2. 9 1. 70 Example 9, Y-I-In 592 1.6 2.96 Example 6, Y-l-In-l-Ho... 720 1.3 3.60 Example 10, Y+In+Ho 720 1. 33. 60

Iodides oi Example 4, Y+T1 319 3.1 1.59 Example 7, Y+T1+Ho 680 1. 4 3.40

We claim:

1. In a process for carrying out a photochemical reaction, especially aprocess for the production of oximes by exposing a solution of acycloal'kane mixed with sulphuric acid to the radiation of a highpressure mercury vapor lamp and adding nitrosyl chloride to saidsolution, the improvement comprising increasing the yield of thereaction by using a doped high pressure mercury vapor lamp emittingenergy having a wavelength lying preponderantly in the range 4000 A. to6000 A. with at least about 77% of the power of said emitted energylying in the range 4500 A. to 5500' A. said doped lamp including adoping mixture comprising,

a mixture of at least one Group 3a metal halide, at least one Group 3bmetal halide and at least one lanthanide metal halide, the total contentof said halides being between about 0.002 mg. and about 1.0 mg. percubic centimeter.

2. A process according to claim 1 wherein the halide of the metal ofGroup 3a is in a ratio by weight of 1/ 2 in relation to theconcentration of the halide of the metal of Group 3b and theconcentration of the halide of the metal of the lanthanide group is in aratio by weight of 1/2 in relation to the concentration of the halide ofthe metal of Group 3a.

3. A process according to claim 1 wherein the doping medium containsyttrium iodide.

4. A process according to claim 1 wherein the doping medium containsindium iodide.

5. A process according to claim 1 wherein the doping medium containsholmium iodide.

6. A process according to claim 1 wherein the doping medium containsyttrium iodide, indium iodide and holmium iodide.

7. A process according to claim 1 wherein the photooximation of acycloalkane'is accomplished.

8. A process according to claim 2 wherein the photooximation of acycloalkane is accomplished.

References Cited UNITED STATES PATENTS Re. 25,937 12/1965 Ito 204- 162 0X 3,141,839 7/1964 Metzger et al. 204162 0 X 3,090,739 5/1963 Ito204-162 0 X 3,309,298 3/ 1967 'Ito et al 204-162 O X 3,312,612 4/1967Choo 204-162 0 X BENJAMIN R. PA'DGETT, Primary Examiner

